Passiflora caerulea - Blue Passion Flower: A Stunning Exotic

Blue Passion Flower

If you’re searching for a fast-growing, visually striking climber to add drama and exotic charm to your outdoor space, Passiflora caerulea—commonly known as the Blue Passion Flower—is an excellent choice. With its captivating white and blue flowers, vigorous growth habit, and hardy nature, this remarkable plant brings a touch of the tropics to UK gardens while being surprisingly resilient. In this comprehensive growing guide, you’ll discover everything you need to know about cultivating, caring for, and maintaining Passiflora caerulea, from choosing the right planting spot to winter protection and propagation tips.

Passiflora caerulea is a semi-evergreen climbing plant native to South America, widely grown in the UK for its striking ornamental appeal and robust nature. ‘Caerulea’ means ‘blue,’ referencing the plant’s spectacular flowers, combining white petals with vibrant blue and purple corona filaments. Blooming profusely from July to September, each flower is a conversation piece, featuring intricate, star-shaped structures that attract bees, butterflies, and curious glances. In addition to its dramatic blooms, the plant produces small, orange, egg-shaped fruits that are technically edible, though their flavour is usually bland.

Known for its fast, sprawling growth, this passion flower can quickly reach heights of up to 10 metres (33 feet) with the right support. This makes it ideal for covering sunny walls, trellises, pergolas, and fences. Thanks to its deeply lobed, glossy green leaves, it also provides year-round structure and foliage interest in milder regions.

Passiflora caerulea should be planted in a warm, sheltered position to ensure healthy growth and a generous flowering display. A south—or west-facing wall is ideal, particularly if it’s protected from cold, drying winds. The reflected heat from bricks or stone can further encourage flowering and reduce winter stress.

This climber thrives in full sun but tolerates partial shade, particularly if it still receives several hours of direct sunlight. Choose a spot that offers sturdy support—such as a trellis, fence, or obelisk—as the plant relies on its tendrils to twine and climb. Be sure to allow enough space, as it can spread several metres wide over time.

Like many climbing plants, the Blue Passion Flower prefers fertile, well-drained soil that retains moisture without becoming waterlogged. Before planting, work plenty of organic matter—such as compost or well-rotted manure—into the soil to boost structure and fertility.

If you’re dealing with heavier clay soils, improve drainage by incorporating coarse grit or planting on a slight mound. Use a loam-based compost like John Innes No. 3 mixed with horticultural grit in containers.

Regular feeding during the growing season will support healthy foliage and flower production. Use a balanced liquid fertiliser every 2–3 weeks from spring through summer, switching to a high-potash feed once flowering begins to encourage more blooms.

Plant Passiflora caerulea in early spring or early autumn when soil temperatures are moderate and rainfall can help with establishment. If growing in a container, select a large pot (at least 40cm wide) with good drainage holes and provide a strong frame or trellis to support the plant.

Set the plant slightly deeper than it was in its nursery pot, and water in thoroughly. Mulching with compost or bark chips will help retain soil moisture and suppress weeds during establishment. Support young stems to help them find and climb the structure, gently tying them in if needed.

The show’s star, of course, is the plant’s intricate flower. From mid-summer to early autumn, Passiflora caerulea produces large, exotic-looking blooms with a unique architecture. The white petals and sepals form a base for vibrant blue and purple corona filaments, while the central structure of stigmas and anthers adds further drama.

Although each flower only lasts a day or two, the plant blooms in succession throughout the season, ensuring continuous colour and interest for weeks. These lightly scented flowers attract pollinators, adding even more wildlife value to your garden.

While Passiflora caerulea is one of the hardiest passion flowers, surviving temperatures as low as -8°C (17°F) may still require protection in colder or exposed parts of the UK. In autumn, apply a thick mulch around the base of the plant to insulate the roots, and consider wrapping the lower stems in horticultural fleece during extended cold spells.

Container-grown plants are more vulnerable to frost, so move them to a sheltered porch, conservatory, or greenhouse over winter where possible. Growing this climber in a container may be the best approach in icy areas, allowing you to bring it under cover when needed.

Passiflora caerulea can be propagated from seed or softwood cuttings. While growing from seed is possible, it can be slow and unpredictable—germination may take 1 to 12 months, and seeds require warmth and moisture.

Taking softwood cuttings in summer is a more reliable method. Choose healthy, non-flowering shoots around 10–15cm long, strip the lower leaves, and insert them into a free-draining propagation mix. Keep the cuttings in a warm, humid environment until roots form—typically in 4 to 6 weeks.

Passiflora caerulea can grow vigorously and even become invasive if not regularly pruned in ideal conditions. Keep growth in check with annual pruning, and monitor for signs of dieback or crowding.

The plant is generally pest- and disease-resistant but may occasionally suffer from aphid infestations or fungal issues, particularly if air circulation is poor. Check leaves regularly, especially during wet summers, and treat any problems promptly using organic methods such as insecticidal soap and neem oil if possible.

The blue passion flower’s bold foliage and exotic flowers make it a natural focal point in any garden design. It pairs beautifully with other sun-loving climbers such as clematis, roses, or trumpet vines.

Consider using it to cover unsightly structures like sheds, utility walls, or fences. Its lush green foliage makes an excellent backdrop for soft pinks, whites, or blue-toned flowers like salvias and agapanthus. It also works well in tropical or Mediterranean-style borders, bringing height, movement, and texture to planting schemes.

I’ve grown Passiflora caerulea in several spots over the years, and it never fails to turn heads—its flowers are some of the most intricate and fascinating in a UK garden. I’ve found it particularly useful for adding fast cover to a bare wall or unsightly fence, and the way it sprawls with such enthusiasm always makes the space feel lush and vibrant. While the fruit isn’t winning any taste awards, the sheer visual drama of the blooms more than makes up for it. Remember to give it a good pruning each spring to keep things in check—I’ve learned that this beauty can take over if left to its own devices! It’ll thrive if you’ve got a warm, sheltered spot, especially against brick. It’s one of those plants I return to repeatedly, especially when I want to inject a tropical feel without compromising hardiness.

• Choose a sunny or partially shaded location
• Provide a strong support structure
• Ensure well-drained soil enriched with organic matter
• Water regularly, but avoid waterlogging
• Prune annually to maintain shape
• Protect from harsh winter conditions
• Monitor growth to prevent spreading
• Allow space for mature size
• Watch for flowering from July to September
• Consider companion plants carefully

Whether you’re training it up a sunny wall, letting it spill over an arch, or growing it in a container on your patio, Passiflora caerulea is an outstanding choice for UK gardeners who want a splash of exotic colour with the reliability of a hardy perennial. With the proper care, this spectacular climber will reward you with years of stunning summer displays, wildlife appeal, and a touch of the tropics in your own back garden.

Check out the RHS article here.

Want to learn about other climbers? Read about Passiflora Purple Rain here.

For more information on climbing plants for your garden, please click here.

Q: What is Passiflora caerulea, and why is it popular in gardens?

A: Passiflora caerulea, commonly known as the Blue Passion Flower, is an exotic-looking evergreen climber cherished for its stunning blue and white flowers. It’s a fantastic choice for gardeners looking to add a splash of colour to their garden.

Q: Are Passiflora caerulea flowers fragrant?

A: Yes, they are slightly fragrant, adding a lovely scent to your garden, particularly in autumn when they are in full bloom. The central purple filaments also make the flowers visually striking!

Q: Can I grow Passiflora caerulea in a pot, or must it be in the ground?

A: You can definitely grow it in a pot! Just ensure it has well-drained soil and plenty of support to climb on. A soil-based potting mix with horticultural grit works wonders if you’re using a container.

Q: How tall can the Blue Passion Flower grow?

A: This fabulous climber can reach heights of up to 10 metres, making it an excellent choice for covering trellises, fences, or even walls in your garden.

Q: What care does Passiflora caerulea need during the colder months?

A: To overwinter your plant, protect it from harsh frost, especially in a cooler climate. You might want to cover the roots with mulch or move potted plants to a sheltered location.

Q: Can I eat the fruit produced by Passiflora caerulea?

A: Yes! The fruit is edible, and while it may not be as sweet as the popular passionfruit (Passiflora edulis), it can still be enjoyed in various dishes or simply eaten fresh!

Q: What other plants are frequently bought with Passiflora caerulea?

A: Gardeners often pair it with other climbing plants or shrubs that thrive in similar conditions. Look for recommendations in your gardening club or nursery’s catalogue for the best companions!